Prepa Charges More Than Double the U.S. Average

SAN JUAN, Puerto Rico—To lower his electricity bills, Francisco Esteves runs the air conditioner in his three-bedroom apartment only briefly on hot summer nights, takes a cold bath before bed and sleeps with a cooling pad in his pillowcase. He stopped using a clothes dryer and replaced his electric stove with a gas-powered one.

His bill in May from the Puerto Rico Electric Power Authority was still a whopper: $130. "I'm going to...